Frustro-conical drilling bit having radially tiered groups of teeth

ABSTRACT

A frustro-conical drilling bit having overlapping tiers of teeth arranged in radial groups. Each main group has an arched nose projection, alternate ones of which depend into a central cavity to define drilling mud channels. Intermediate teeth groups are positioned between the main groups and each is closer to the following main group in the direction of rotation.

United States Patent 1 Rederon 1 Oct. 30, 1973 1 1 FRUSTRO-CONICAL DRILLING BIT HAVING RADIALLY TIERED GROUPS OF TEETH [75] Inventor: Christian Rederon,

Neuilly-sur-Seine, France [73] Assignee: Compagnie Francaise Des Petroles,

Paris, France [22] Filed: May 2, 1972 [21] Appl. No.: 249,578

[30] Foreign Application Priority Data May 4, 1971 France 1. 7115966 52 us. Cl. 175/329, 175/409 [51] Int. Cl E21b 9/36 [58] Field of Search 175/329, 330, 391, 175/409, 410

[56] References Cited UNITED STATES PATENTS 2,607,562 8/1952 Phipps 175/391 2,894,726 7/1959 Weaver et a1 175/391 3,127,945 4/1964 Bridwell et a1... 175/329 3,135,341 6/1964 Ritter 175/329 3,181,632 5/1965 Raynal 175/329 3,599,736 8/1971 Th0mps0n.... 175/329 3,696,875 10/1972 Cortes 175/410 X Primary ExaminerDavid H. Brown Att0rney-Ri chard C. Sughrue et al.

57 ABSTRACT A frustro-conical drilling bit having overlapping tiers of teeth arranged in radial groups. Each main group has an arched nose projection, alternate ones of which depend into a central cavity to define drilling mud channels. Intermediate teeth groups are positioned between the main groups and each is closer to the fol lowing main group in the direction of rotation.

9 Clairns, 4 Drawing Figures PATENTEUUBT 30 I915 SHEET 10F 2 PATENTEDnmao I973 3.788.581

SHEET 2 OF 2 FRUSTRO-CONICAL DRILLING BIT HAVING RADIALLY TIERED GROUPS OF TEETH BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a high efficiency drilling tool or bit with a long life expectancy having attack projections distributed over the entire surface of the tool.

2. Description of the Prior Art French Pat. No. 69.07864, published under N0. 2.029.963 in the name of Compagnie Francaise des Petroles, describes a high efficiency drilling tool which is especially noteworthy due to the fact that its structure and the materials used allow very high progress rates to be obtained, irrespective of the type of ground drilled through, whether this be hard rock or clayey ground tending to clog the tools.

SUMMARY. OF THE INVENTION The aim of the invention is to further increase the life expectancy of this type of drilling tool, that is, a tool having attack projections distributed over its entire surface and having a central hollow zone containing the drilling mud delivery channels. The invention is characterized in that the projections form ascending tiers extending from the base to the nose of the tool when in a vertical position, but in the opposite direction in its drilling position. The tiers are divided in radial groups of projections, each having, at least with the exception of the projections at the nose ofthe tool, two radial surfaces, a peripheral surface and an upper surface, such that the leading radial surface, with respect to the direction of rotation of the tool, of each projection of the same radial group interrupts the upper surface of the lower adjacent projection.

Experience has shown that with this type of structure the tool retains a high degree of efficiency. In addition, the wear of the tool is reduced considerably. In particular, it has been found that circulation of the mud allows all debris torn away by each of the projections to be discharged without any clogging of parts of the upper surfaces recessed from the peripheral surfaces of the adjacent projections and in addition allows better cooling of all the active parts of the attack surfaces. Another aim of the invention is to provide a tool of this type, in which the upper or nose projections of the tool have leading radial surfaces which cut across the upper surfaces of the tiered projections and extend into the central hollow part of the tool such that each mud delivery channel orifice is separated from the adjacent orifice by at least one of the projections adjacent to it.

In this way a'series of separate mud delivery channels is obtained which may be supplied with drilling mud by means of equal diameter orifices joined to the channels and having the same flow rate soas to distribute the mud in a uniform and constant manner over the entire periphery of the tool nose.

Another aim of the invention is to provide a tool of this type in which the surfaces between two projections on the nose of the tool consiyt of shoulders extending in a sloping manner from one part of the trailing radial surface close to the upper ridge of a projection to the bottom of the leading radial surface of the adjacent projection. As a result, the mud coming from the hollow central part of the tool and passing between the projections tends to flow onto the leading radial surface of the adjacent projection and from there to a part of the horizontal surface of the lower adjacent projection.

Another aim of the invention is to provide a tool of this type in which the number of groups of tiered projections is increased by disposing an intermediate radial group between each two radial groups extending from a nose projection of the tool to its base. The distance between the leading radial surfaces of the projections of the intermediate group and the trailing surfaces of the projections of the adjacentradial group is greater than the distance between the trailing surfaces of the intermediate group and the leading surfaces of the adjacent projections of the other adjacent radial group. In other words, the intermediate groups are not disposed midway between adjacent radial groups.

Experience has shown that by increasing the number of projections while maintaining the tiered arrangements, the efficiency of the tool is increased. At the same time, near perfect irrigation of the drilling mud over all the attack surfaces is maintained. The more rapid circulating speed of the mud in the tiered furrows ensures both total removal of the dislodged ground and excellent cooling.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a perspective view of the tool;

FIG. 2 is a schematic plan view showing the arrangement of the radial groups of projections;

FIG. 3 is a view along the line III-III of FIG. 2; and

FIG. 4 is a diagrammatic view of the peripheral surface of a projection.

DESCRIPTION OF A PREFERRED EMBODIMENT The perspective view of FIG. 1 shows the tool resting on the base of the threaded connection 1 which allows it to be screwed onto the appropriate shaft. Each projection 2 comprises an upper surface 2a, a peripheral surface 2b, a leading radial surface 20 and a trailing surface 2d. In the preferred embodiment, these surfaces are flat. The radial surfaces are bordered by shoulders.

The projections are disposed in radial groups, such as those represented by 3 and 4, consisting respectively of projections 5 to 9 and 10 to 14. These groups, which include projections 9 and 14 of the nose of the tool, are separated by intermediate radial groups, such as group 33 consisting of projections 15 to 18.

In addition to their radial disposition, the projections are disposed in crowns. In the example selected the projections 5 to 8, 10 to 13 and 15 to 18 are disposed on four crowns or tiers. The projections 5, 15 and 10 are disposed on the crown with the largest diameter and the projections 8, l8 and 13 on the crown having -internal extension in the central part.

At the bottom of the central cavity 21 are four orifices 22 to 25, FIG. 2, into which open the mud delivery channels. Each of the projections 14, 20, 26 and 27 separates two adjacent orifices. For example, the end of the projection 14 separates the orifices 22 and 25.'

The internal extensions of the other projections 9, 19, etc. stop at the wall of the hollow part at some distance from the bottom to allow the free passage of the ground dislodged and drained by the mud. As the mud passes through the orifices it is channeled to ensure a steady flow between the internal extensions of the projections of the various radial groups.

The projections are inclined, as shown in FIG. 4, to present a cutting angle of between 6 and 14. All the outer projections rise above lower surfaces which are slightly recessed with respect to their outer peripheral surfaces as may be seen in FIG. 3. Furthermore, all the peripheral surfaces, such as 28b in FIG. 3, for example, are slightly inclined on the horizontal surface 29a of the next lower projection at an angle of 1 to 6. In FIG. 3 the line 30 represents the profile of the tool between two radial groups of projections.

Each projection may be strengthened on its trailing radial surface by a shoulder starting from an adjacent part of the upper edge of the radial surface and extending in a sloping manner and joining together at the base of the leading radial surface of the subsequent projection.

The leading and trailing radial surfaces of each projection at the nose of the tool may comprise shoulders which join together with the shoulders of the adjacent projections such that the connection of the shoulders, such as 31 between the projections 9 and 14, is disposed in the lowest region of the nose. This region is used for the passage of the drilling mud which flows between the radial groups. It may also be moved slightly towards the leading radial surface of the projection directly following it with respect to the direction of rotation of the tool.

As the zone connecting a shoulder 32, for example, of the trailing radial surface of a projection 18 with the leading radial surface of the subsequent projection 8 intersects the horizontal surface of the projection 7 behind the line of intersection of the projection 8 with the horizontal surface of the projection 7, the mud flowing between two projections 9 and 14 at the nose of the tool tends to sweep across the successive shoulders disposed radially in series and across the radial leading and horizontal surfaces of each projection, thus eliminating any danger of clogging.

It is also to be noted that the intermediate group 33 which is disposed between the radial groups 3 and 4 is closer to group 3 than to group 4, such that the flow of mud circulating between the projections 9 and 14 divides appropriately into a first current between the groups 3 and 33 and into a second current between the groups 33 and 4 instead of flowing primarily in the area between groups 3 and 33.

The lines at the intersection of the horizontal and peripheral surfaces of the projections of the same radial group are in the same plane. This arrangement allows the forces exerted by each projection to be better distributed.

As a further alternative, the projections of the intermediate groups may be staggered towards the top or the bottom to an extent approximating the size of the diamonds used. These diamonds may be embedded in the metal forming the attack surfaces of the projections. By way of example, this stagger may vary from 1 to a few millimeters. This particular arrangement makes it possible to increase the drilling depth capable of being obtained without raising the tool, irrespective of the differences and features of the ground encountered, while at the same time maintaining a high drilling speed. In fact, experience has shown that this arrangement even permits drilling through the actual thick strata of the upper earth formations without any considerable wear of the projection work surfaces so that when the lower hard strata are encountered, even if part of the work surfaces of the projections of the staggered groups towards the nose of the tool show signs of wear, the drilling tool still performs in an excellent manner since the stresses begin to affect only the projections of the groups which are recessed with respect to the nose of the tool. This slight stagger further aids the mud flow, thus increasing the wear resistance of the tool.

- What is claimed is:

1. A drilling tool comprising a frustro-conical body bearing attack projections of metal teeth embedded with diamonds, each tooth having an outer peripheral surface with respect to the axis of the tool, front and rear radial surfaces and an upper surface intersecting the radial and peripheral surfaces, the teeth being disposed in concentric, tiered groups, orifices in the tool body for supplying drilling mud, the teeth being further arranged in radial rows, the peripheral surface of each tooth in the same radial row interrupting the upper surface of the lower adjacent tooth.

2. A drilling tool as claimed in claim 1, wherein the teeth of the radial rows are disposed in such a manner that the surface of the body of the tool between two consecutive projections forms a surface of tiers staggered both towards the base of the tool and towards its axis with respect to the tiers formed by the upper and peripheral surfaces of each tooth of the same radial row.

3. A drilling tool as claimed in claim 1 wherein the front radial surface of each tooth is inclined with respect to the tool axis at an angle of between 6 and 14.

4. A drilling tool as claimed in claim 1, wherein the outer peripheral surface of each tooth is inclined with respect to the tool axis at an angle of 1 to 6.

5. A drilling tool as claimed in claim 1, wherein the trailing edges of the upper surface of at least the three outermost teeth in the same radial row are substantially in the same plane.

6. A drilling tool as claimed in claim 1, wherein the upper surfaces of the teeth of the same concentric group are in the same plane.

7. A drilling tool as claimed in claim 1 wherein the peripheral surfaces of the teeth of the same concentric group define a generally conical surface.

8. A drilling tool as claimed in claim 1, wherein the front radial surface of each tooth in the same radial row intersects the upper surface of the lower adjacent tooth.

9. A drilling tool as claimed in claim 8, wherein the body also has a tiered configuration, and the front part of the upper surface of each tooth extends towards the axis of the tool as far as the peripheral surface of a body tier situated between two consecutive radial rows of teeth. 

1. A drilling tool comprising a frustro-conical body bearing attack projections of metal teeth embedded with diamonds, each tooth having an outer peripheral surface with respect to the axis of the tool, front and rear radial surfaces and an upper surface intersecting the radial and peripheral surfaces, the teeth being disposed in concentric, tiered groups, orifices in the tool body for supplying drilling mud, the teeth being further arranged in radial rows, the peripheral surface of each tooth in the same radial row interrupting the upper surface of the lower adjacent tooth.
 2. A drilling tool as claimed in claim 1, wherein the teeth of the radial rows are disposed in such a manner that the surface of the body of the tool between two consecutive projections forms a surface of tiers staggered both towards the base of the tool and towards its axis with respect to the tiers formed by the upper and peripheral surfaces of each tooth of the same radial row.
 3. A drilling tool as claimed in claim 1 wherein the front radial surface of each tooth is inclined with respect to the tool axis at an angle of between 6* and 14*.
 4. A drilling tool as claimed in claim 1, wherein the outer peripheral surface of each tooth is inclined with respect to the tool axis at an angle of 1* to 6*.
 5. A drilling tool as claimed in claim 1, wherein the trailing edges of the upper surface of at least the three outermost teeth in the same radial row are substantially in the same plane.
 6. A drilling tool as claimed in claim 1, wherein the upper surfaces of the teeth of the same concentric group are in the same plane.
 7. A drilling tool as claimed in claim 1 wherein the peripheral surfaces of the teeth of the same concentric group define a generally conical surface.
 8. A drilling tool as claimed in claim 1, wherein the front radial surface of each tooth in the same radial row intersects the upper surface of the lower adjacent tooth.
 9. A drilling tool as claimed in claim 8, wherein the body also has a tiered configuration, and the front part of the upper surface of each tooth extends towards the axis of the tool as far as the peripheral surface of a body tier situated between two consecutive radial rows of teeth. 